Nooksack River Watershed Vision and Implementation Strategies
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Nooksack River Watershed Vision and Implementation Strategies Introduction. A number of plans related to floodplains and floodplain management have been prepared for the Nooksack River Watershed. The Comprehensive Flood Hazard Management Plan (CFHMP, 1999) examined flood issues and potential risk BENEFITS OF INTEGRATED reduction options for the mainstem Nooksack FLOODPLAIN MANAGEMENT downstream of Deming. This plan acknowledged the Salmon Habitat and need to recover healthy salmon populations, including Floodplain Process species soon to be listed under the Endangered Species Improvements Act, but did not provide specific recommendations on Flood Risk Reduction: Rural how this would be accomplished. The 2005 WRIA 1 residential, municipal, agricultural, Lummi Nation Salmonid Recovery Plan provides the roadmap to and Nooksack Indian Tribal recover two populations of ESA listed spring Chinook lands salmon and other salmonid populations and includes Shellfish Bed Protection specific habitat protection and restoration Agricultural Improvements recommendations. However, detailed assessments were Water Quality Improvements not available for the river downstream of Deming. Thus, Understanding of Sediment the habitat recommendations are less detailed and the Dynamics Transportation potential interactions between the flood risk reduction system and desired habitat actions were not analyzed. While residential, commercial, municipal, and industrial developments are all present on the floodplain, agriculture is still the main floodplain land‐use along the mainstem and lower South Fork. Neither plan described above fully incorporates impacts, either positive or negative, of flood risk reduction or salmon habitat recovery actions to on‐going agricultural uses or to fisheries resources. This document and the flood plan update scheduled to begin in 2016 provide the opportunity to: Refine our understanding of lower river habitat limitations and to develop more specific habitat restoration strategies Identify specific on‐the‐ground habitat restoration opportunities Identify how flood risk reduction actions can “integrate” with recovering floodplain ecosystem processes and functions PAGE | 1 of 44 FINAL 9.29.15 Describe how actions for flood and fish can integrate with agricultural activities and how the greatest public benefit to all three might be derived Provide a forum for this community to refine how it wants to manage floodplains and to put into place the necessary policies, procedures, actions and the funding to support implementation. This document was prepared over a three month period by members of the interagency coordination team that was assembled to develop a System‐wide Improvement Framework (SWIF), a plan to address levee deficiencies along the river. Much more stakeholder coordination including resolving disparities in the policies and directions of different jurisdictions and interest groups will be needed to turn this somewhat fuzzy vision into a comprehensive plan that addresses the range of issues involved in river management along the Nooksack River. It should also be noted that the WRIA 1 Local Integrating Organization is currently preparing a 5‐year Recovery Plan to identify how the Puget Sound Partnership’s Action Agenda is being implemented locally. That plan includes restoration of floodplains and will be completed in fall 2016. It is intended that this document will support that product and will provide a unified “vision” for floodplains. Watershed Overview. Originating on the flanks of Mount Baker and the Twin Sisters Range in the Mount Baker‐Snoqualmie National Forest, the upper forks of the Nooksack River converge near Deming to form the lower Nooksack River. From the confluence of the North and South forks near Deming to its outlet in Bellingham Bay, the lower river flows for approximately 37 miles across a primarily agricultural floodplain. There are three upper forks that join to form the lower mainstem of the Nooksack near Deming. The North Fork receives drainage from the north side of Mount Shuksan (9,131’) and Mount Baker (10,781’) and flows through forest lands above a relatively confined upper valley and then through a relatively unconfined valley downstream of Maple Falls. This lower reach has some agriculture and rural residential development downstream to its confluence with the Middle Fork about four miles upstream of Deming. The Middle Fork drains forest lands on the southwestern flanks of Mount Baker and the eastern side of the Twin Sisters Range in a narrow valley and then flows through a relatively unconfined rural residential valley in the lower 5 miles. Unlike the other two forks that originate on Mt. Baker and receive glacial meltwater in the summer and fall, the South Fork is not glacially influenced as it originates in the Twin Sisters Range southwest of Mount Baker. From the Sisters, it flows southerly through forest lands in a confined valley into Skagit County, then to the west and north and back into Whatcom County, where the valley widens appreciably near the Saxon area. Commercial forestry is the dominant land‐use in the upper South Fork while downstream, the floodplain is intensively farmed with areas of low‐density rural residential development and the community of Acme; few levees are present, though much of the river bank is armored to prevent channel migration. PAGE | 2 of 44 FINAL 9.29.15 Below its confluence with the South Fork, the mainstem Nooksack comes out of the Cascade foothills carrying a high sediment load, which is evident in the large braided sections in the lower North and Middle Forks. Downstream of Deming the valley widens and the gradient decreases as the river leaves the mountains and flows to Bellingham Bay. Although the Nooksack only ranks 4th in terms of mean annual discharge, the USGS estimates the annual sediment load for the Nooksack River at 1.4 million tons, the second largest of all the rivers draining to the Puget Sound region. This relatively large sediment volume relates to the river’s origins in the steep and unstable North Cascades including the glaciated flanks of Mt. Baker and Mt. Shuksan. The river flows through Nooksack Tribal lands, then through primarily agricultural lands from Deming down to Bellingham Bay, passing the community of Deming and the cities of Everson, Lynden and Ferndale. It then flows through the Lummi Indian Reservation before discharging to Bellingham Bay. While much of the river is leveed, the levees within the agricultural areas generally allow for overtopping during events as frequent as a 5‐year flow (i.e., the flow level with a 20 percent chance of occurring during any given year). Levees adjacent to developed areas generally provide a higher level of protection, although infrastructure is still at risk due to gaps in the protection or lower levee sections upstream that allow flood flows to enter the floodplain. There are currently 1,948 parcels with improvements and another 1,935 parcels without improvements in the Nooksack River floodplain. There are approximately 18 unmitigated repetitive loss properties and 1 severe repetitive loss property in the basin. However, essentially the entire Nooksack valley is considered at risk to flooding, and many feet of roadway and acres of agricultural lands flood several times a flood season. These numbers reflect parcels that get wet, but lateral river movement, or channel migration, is another process that poses challenges to Nooksack River management. Channel migration is an important salmon habitat‐forming process, recruiting large wood and forming and maintaining critical floodplain habitats including sloughs and side channels. Yet channel migration can also be a threat to existing public and private infrastructure, and is the reason behind many miles of bank armor already present in the forks and the lower mainstem. A critical challenge before this community will be to synthesize the technical data necessary to better understand channel migration processes and then develop a common vision on how to provide for channel migration and its positive ecological benefits while protecting existing public and private floodplain investments where necessary, and planning for future floodplain development if appropriate. PAGE | 3 of 44 FINAL 9.29.15 The floodplains in the lower Nooksack River and its forks support populations of Endangered Species Act listed Chinook salmon, steelhead, and bull trout along with coho, chum, pink, and sockeye salmon, sea‐run cutthroat trout.. These are Treaty protected resources of critical importance to the Tribes and to maintaining the quality of life for non‐ tribal members too. Populations are critically low for many of these salmonid species with recovery of both populations of Nooksack spring Chinook considered essential to delisting of the Puget Sound Chinook salmon Evolutionarily Significant Unit (ESU). Salmon populations and shellfish growing and harvest areas in Portage Bay (in the southwest corner of Bellingham Bay) and in Lummi Bay have been impacted by the historic and current land use and the correlated effects on river system functions and floods. These changes affect both habitat and water quality. The cumulative effects of upstream management combined with heavy alteration of some reaches of the Nooksack River by the flood control system limits population productivity of the salmonids native to this river system. Many of the levees along the lower Nooksack River are currently eligible for repair through the U.S. Army Corps of